doesn't keep settings. shuts off by itself so your ip is revealed. Don't count on this for protection. and if you do use it check it each time to make sure it's turned on and working.

By default this shield is turned off. I need to turn it on every time I open browser

very good

Don't know yet!

Does precisely what it says on the tin. You can go to the options page with this setting and see it toggle in realtime with the extension, which provides a much more convenient means of switching it for those rare times you might want it off, i.e. Google Voice.